Fernandez, Yelich and Heaney are Marlins' first-round draft picks. Marisnick, Nicolino and Hechavarria arrived earlier this offseason in the blockbuster trade with the Blue Jays that sent Josh Johnson, Jose Reyes, Mark Buehrle, Emilio Bonifacio and John Buck north.

"It's just experience, playing at the higher level," President of Baseball Operations Larry Beinfest said of Fernandez and Yelich, both of whom are expected to open the season at Double-A Jacksonville. "There's not a defined flaw for either one that we've identified.

"I know Christian has worked very hard on his throwing mechanics and done a great job adjusting to center field. They've done everything we've asked of them. To achieve at the level they've achieved already, there's always things you can refine but the basics are there for them to be very successful."

Fernandez and Yelich both will be in big league camp.

"It's definitely going to be an exciting spring training," Yelich said. "I think you have to approach it the same way, the way you go about any spring training. This one will probably have a little more significance to it...I feel like if I take care of business [at Double-A] everything else should fall into place."